"I knew exactly what I was getting into," Cavallari said. "I knew exactly the character they wanted me to be, so I said, 'I'm game. What do you want me to do?'"

For starters, she said, they asked her to stage a relationship with Brody Jenner, her real-life ex-boyfriend who was dating model Jayde Nicole at the time.

"They pretended like him and Jayde broke up and I was dating Brody, and then Jade and I got in a huge fight because she saw us out at the club, which wasn't real at all," she said. "They were together the entire time."